Linearly translating agitators for processing microfeature workpieces, and associated methods

ABSTRACT

Systems and methods for processing microfeature workpieces with agitators are disclosed. A system in accordance with one embodiment includes a vessel configured to receive a processing fluid at a process location, a fluid inlet positioned to direct the processing fluid into the vessel, a weir positioned above the process location and outwardly from the fluid inlet to receive the processing fluid moving radially outwardly from the inlet, and a workpiece support positioned to carry a workpiece at the process location. An agitator has an elongated agitator element positioned proximate to the process location, a first support proximate to a first end of the agitator element, and a second support proximate to an opposite end of the agitator element. A motor is coupled to the first support and not the second support to drive the agitator along a linear path relative to the process location. A linear guide is engaged with the second support to guide the motion of the agitator.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part of pending U.S. application Ser. No. 10/734,098, filed on Dec. 11, 2003, which claims priority to U.S. Provisional Application No. 60/484,603, filed on Jul. 1, 2003, both of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention is related to linearly translating agitators for processing microfeature workpieces, and associated methods. Such agitators and associated support arrangement provide high mass-transfer rates at the workpiece surface, while maintaining a consistent spacing from the workpiece surface.

BACKGROUND

In many wet chemical processes, a diffusion layer forms adjacent to a process surface of a workpiece (e.g., a semiconductor wafer). The mass-transfer in the diffusion layer is often a significant factor in the efficacy and efficiency of wet chemical processing because the concentration of the material varies over the thickness of the diffusion layer. It is accordingly desirable to control the mass-transfer rate at the workpiece to achieve the desired results. For example, many manufacturers seek to increase the mass-transfer rate to increase the etch rate and/or deposit rate, thereby reducing the time required for processing cycles. The mass-transfer rate also plays a significant role in depositing alloys onto microfeature workpieces because the different ion species in the processing solution have different plating properties. Therefore, increasing or otherwise controlling the mass-transfer rate at the surface of the workpiece is important for depositing alloys and other wet chemical processes.

One technique for increasing or otherwise controlling the mass-transfer rate at the surface of the workpiece is to increase the relative velocity between the processing solution and the surface of the workpiece, and in particular, the relative velocity of flows that impinge upon the workpiece (e.g., non-parallel flows). Many electrochemical processing chambers use fluid jets or rotate the workpiece to increase the relative velocity between the processing solution and the workpiece. Other types of vessels include paddles that translate or rotate in the processing solution adjacent to the workpiece to create a high-speed, agitated flow at the surface of the workpiece. In electrochemical processing applications, for example, the paddle typically oscillates between the workpiece and an anode in the plating solution.

One arrangement for agitating the flow adjacent to a workpiece includes oscillating a single paddle back and forth across the diameter of the workpiece. For example, U.S. Pat. No. 6,547,937, assigned to the assignee of the present invention and incorporated herein by reference, discloses a single elongated paddle driven at opposing ends by a motor and belt arrangement. Though suitable for many purposes, this arrangement requires relatively high paddle speeds in some instances because it includes only a single paddle. Driving the paddle from both ends can also result in one end or the other binding if the drive mechanism is not precisely synchronized.

One approach to addressing the foregoing drawbacks is to replace the single paddle with an array of paddles, as is disclosed in U.S. Patent Publication No. US2005-0006241A1, also assigned to the assignee of the present invention and incorporated herein by reference. The array of paddles is carried at one end and cantilevered across the diameter of the workpiece. The array of paddles can be reciprocated over a much shorter stroke than a single paddle while still providing suitable agitation adjacent to the workpiece. However, in some cases, the cantilevered arrangement of the paddle array results in some parts of the paddles (e.g., those near the supported end of the array) maintaining a closer spacing relative to the workpiece than are other parts of the paddles (e.g., those near the unsupported, cantilevered end of the array).

In light of the foregoing, it would be desirable to provide an apparatus and method for agitating the processing solution adjacent to a workpiece in a manner that provides consistent spacing between the agitator and the workpiece, and that does not require high agitator speeds and/or extended agitator translation distances. It would also be desirable to improve the manner with which fluid is provided to the interface between the agitator and the workpiece.

SUMMARY

The present invention provides agitators and associated systems and methods that are capable of providing the desired degree of agitation at the workpiece surface, while maintaining consistent spacing between the agitator and the workpiece. The agitators accordingly have one or more elongated agitator elements, with a first support proximate to a first end of the agitator elements and a second support proximate to a second end of the agitator elements. A motor is coupled to the first support and not the second support to drive the agitator along a linear path relative to the process location. A linear guide is then engaged with the second support. By not driving the agitator from both ends, the likelihood for binding the agitator is reduced or eliminated. By providing a linear guide opposite the driven end of the agitator, the spacing between the agitator elements and the workpiece is maintained across the surface of the workpiece.

In particular arrangements, the linear guide is positioned to (a) restrict movement of the agitator toward and away from the process location along a first axis, and (b) allow linear translation of the agitator along the linear path, which is aligned with a second axis generally perpendicular to the first. The linear guide can also (c) allow for movement of the agitator along a third axis generally perpendicular to both the first and second axes to at least reduce the tendency for the agitator to bind with the linear guide. For example, the linear guide can include a U-shaped channel having an upwardly facing opening, and the channel can carry rollers connected to the second support. At least one roller is positioned to be in contact with one of the walls of the channel, while another roller is not, thereby allowing for at least some motion along the third axis.

In operation, a processing fluid is directed upwardly into a vessel toward a microfeature workpiece positioned at a process location. The processing fluid is then directed radially outwardly adjacent to the microfeature workpiece and over a weir. The processing fluid adjacent to the microfeature workpiece is agitated with an agitator by driving the first support along the linear guidepath and guiding the second support without driving the second support. The motion of the agitator toward and away from the process location is at least restricted along the first axis, permitted along a second axis (e.g., a reciprocation axis) generally transverse to the first axis, and permitted along a third axis generally perpendicular to both the first and second axes at least to an extent that reduces or eliminates binding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top isometric view of a tool having one or more process chambers with an agitator configured in accordance with an embodiment of the invention.

FIG. 2A is a cut-away view of one of the process chambers shown in FIG. 1.

FIG. 2B is a detailed, cut-away view of a portion of the process chamber shown in FIG. 2A.

FIG. 3A is a top isometric view of a paddle assembly and associated housing and support arrangement configured in accordance with an embodiment of the invention.

FIG. 3B is a bottom view of the assembly, housing and support arrangement shown in FIG. 3A.

FIG. 3C is a cross-sectional illustration of the assembly, housing and support arrangement, taken substantially along line 3C-3C of FIG. 3A.

FIG. 4 is a top isometric view of the process chamber shown in FIG. 2, illustrating a motor and linear guide coupled to an agitator in accordance with an embodiment of the invention.

FIG. 5A is an exploded isometric illustration of the linear guide shown in FIG. 4.

FIG. 5B is a cross-sectional illustration of the linear guide shown in FIG. 4.

FIG. 5C is a cross-sectional illustration of the linear guide, taken substantially along line 5C-5C of FIG. 5B.

DETAILED DESCRIPTION

The following description discloses the details and features of several embodiments of agitators used for processing microfeature workpieces, and associated methods for making and using such agitators. The term “agitator” refers to a device that accelerates, stirs and/or otherwise energizes flow adjacent to a microfeature workpiece. The terms “microfeature workpiece” and “workpiece” refer to substrates on and/or in which micro-devices are formed. Typical micro-devices include microelectronic circuits or components, thin-film recording heads, data storage elements, micro-fluidic devices, and other products. Micro-machines or micromechanical devices are included within this definition because they are manufactured in much the same manner as are integrated circuits. The substrates can be semiconductive pieces (e.g., silicon wafers or gallium arsenide wafers), non-conductive pieces (e.g., various substrates), or conductive pieces (e.g., doped wafers). It will be appreciated that several of the details set forth below are provided to describe the following embodiments in a manner sufficient to enable a person skilled in the art to make and use the disclosed embodiments. Several of the details and advantages described below, however, may not be necessary to practice certain embodiments of the invention. Accordingly, the invention may also include other embodiments that are also within the scope of the claims, but are not described in detail with reference to FIGS. 1-5C.

The operation and features of agitators used for processing microfeature workpieces are best understood in light of the environment and equipment in which they can be used. Accordingly, a representative processing tool in which the agitators can be used is described with reference to FIG. 1. Further details of representative agitators and devices for driving and guiding the agitators are then described with reference to FIGS. 2A-5C.

FIG. 1 is a partially schematic, isometric illustration of a tool 100 that performs one or more wet chemical or other processes on microfeature workpieces W. The tool 100 includes a housing or cabinet (removed for purposes of illustration) that encloses a deck 104. The deck 104 supports a plurality of processing stations 110, and a transport system 105. The stations 110 can include rinse/dry chambers, cleaning capsules, etching capsules, electrochemical deposition chambers, annealing chambers, or other types of processing chambers. At least some individual processing stations 110 include a vessel, reactor, or chamber 130 and a workpiece support 120 (for example, a lift-rotate unit) that supports an individual microfeature workpiece W during processing at the chamber 130. The transport system 105 moves the workpieces W to and from the chambers 130. Accordingly, the transport system 105 includes a transfer device or robot 106 that moves along a linear guidepath 103 to transport individual workpieces W within the tool 100. The tool 100 further includes a workpiece load/unload unit 101 having a plurality of containers for holding the workpieces W as they enter and exit the tool 100.

In operation, the transfer device 106 includes a first carrier 107 with which it carries the workpieces W from the load/unload unit 101 to the processing stations 110 according to a predetermined work flow schedule within the tool 100. Typically, each workpiece W is initially aligned at a pre-aligner station 110 a before it is moved sequentially to the other processing stations 110. At each processing station 110, the transfer device 106 transfers the workpiece W from the first carrier 107 to a second carrier 121 located at the support 120. The second carrier 121 then carries the workpiece W while the workpiece W is processed at the corresponding process chamber 130. A controller 102 receives inputs from an operator and, based on the inputs, automatically directs the operation of the transfer device 106, the processing stations 110, and the load/unload unit 101.

FIG. 2 is a cut-away illustration of one of the process chambers 130 shown in FIG. 1. The process chamber 130 generally includes a vessel 131 that contains an electrochemical processing fluid for processing a workpiece W, a cut-away portion of which is shown in dashed lines in FIG. 2A). The vessel 131 has a lower portion 139 a through which the processing fluid enters, and an upper portion 139 b having a horizontal process location P at which the workpiece W is processed. The processing fluid enters the vessel 131 through a fluid inlet 134 at the lower portion 139 a and proceeds generally upwardly toward the process location P through a flow control assembly 138. The fluid at the process location P is in fluid and electrical communication with one or more electrodes 133, three of which are located below the process location P and are identified as first, second and third electrodes 133 a, 133 b and 133 c, respectively. Accordingly, the lower portion 139 a functions as an electrode support. Each electrode 133 a-133 c is housed in an annular chamber 132 having upwardly extending walls that terminate near the process location P. The electrodes 133 a-133 c, each of which can be independently controlled, operate as anodes and act at corresponding “virtual anode” locations positioned at the open tops of each electrode chamber 132. A ring contact assembly 122 acts as a cathode and provides a return path for current passing from the electrodes 133 a-133 c, through the electrochemical fluid and through the workpiece W. Alternatively, the return path can be provided by a backside contact, which contacts the upwardly facing, back surface of the workpiece W. After processing, the workpiece W can be rinsed and spun dry, typically referred to as a spin/rinse/dry or SRD process. An SRD lip 137 captures fluid flung from the workpiece W during the SRD process.

The vessel 131 also includes an agitator 140 positioned just below the workpiece W at the process location P. The agitator 140 includes multiple, elongated and spaced-apart agitator elements 142 that reciprocate back and forth as a unit within an agitator housing 141, as indicated by arrow R. The agitator housing 141 includes a first weir 135 over which the processing fluid flows in a radial direction after it passes upwardly through the vessel 131 and outwardly across the surface of the workpiece W. The agitator housing 141 defines a portion of an agitator chamber 129 in which the agitator 140 reciprocates, with a lower portion of the agitator chamber 129 formed at least in part by the tops 127 of the electrode chambers 132, and an upper portion of the chamber formed at least in part by the workpiece W.

The chamber 130 also includes a magnet assembly 170, which in turn includes two magnets 171 positioned on opposite sides of the vessel 131. The magnets 171 provide a magnetic field within the vessel 131 that magnetically aligns material in the processing fluid, e.g., as the material is deposited onto the workpiece W. In other embodiments, the chamber 130 need not include the magnet assembly 170, while still including other features described herein.

The overall process chamber 130 further includes a fourth electrode 133 d positioned close to the process location P. The fourth electrode 133 d may be coupled to a potential at a polarity opposite that to which the first-third electrodes 133 a-133 c are coupled (e.g., a cathodic potential). Accordingly, the fourth electrode 133 d may operate as a current thief, thereby attracting material that would otherwise be deposited at the periphery of the workpiece W. In this manner, the fourth electrode 133 d can counteract the “terminal effect,” which typically results when the workpiece (a) is carried by the ring contact assembly 122 and (b) has a relatively high-resistance conductive layer exposed to the processing fluid. The fourth electrode 133 d is carried by a second weir 136 over which at least some of the processing fluid may flow. Further details of this arrangement are described below with reference to FIG. 2B, and additional details of the agitator 140 are then described with reference to FIGS. 3A-5C.

FIG. 2B is an enlarged isometric illustration of the upper portion 139 b of the process chamber 130 shown in FIG. 2A. The agitator housing 141 seals against the upper portion 139 b with a seal 128 (e.g., an O-ring seal). As shown in FIG. 2B, the ring contact assembly 122 includes a ring contact 123 (shown schematically in FIG. 2B) having contact elements that make electrical contact with the downwardly facing periphery of the workpiece W carried at the process location P. Typically, the ring contact 123 is coupled to a cathodic potential, so that the workpiece W is cathodic, but the ring contact 123 may selectively be coupled to an anodic potential as well. The ring contact assembly 122 also includes a ring contact seal 124 that protects the interface between the ring contact 123 and the workpiece W. The ring contact assembly 122 is carried by the support 120 (FIG. 1) and accordingly moves upwardly and downwardly relative to the vessel 131 to move the workpiece W to and from the process location P.

While at the process location P, the workpiece W is in contact with the electrochemical fluid proceeding upwardly through openings between neighboring agitator elements 142, radially outwardly through the vessel 131, and then over the first weir 135 and the second weir 136. At the same time, the agitator 140 reciprocates back and forth so that the agitator elements 142 agitate the fluid near the workpiece W. Each agitator element 142 has a diamond shape, with two oppositely-facing tapered ends, in the illustrated embodiment. In other embodiments, the agitator elements 142 have other shapes (e.g., a tapered shape, with a generally sharp end facing toward the workpiece W and a generally blunt end facing the opposite direction). Fluid passing over the first weir 135 contacts the fourth electrode 133 d (e.g., the thief electrode) to provide electrochemical communication between the fourth electrode 133 d and the peripheral region of the workpiece W. The close proximity between the fourth electrode 133 d and the peripheral region of the workpiece W is expected to provide greater control over the effects of the fourth electrode 133 d, and additional benefits described in greater detail in pending U.S. application Ser. No. ______ (Attorney Docket No. 291958257US), filed concurrently herewith and incorporated herein by reference. Fluid passing over the second weir 136 keeps the second weir 136 wet and can thereby prevent the formation of crystals, which may interfere with the proper seating between the ring contact assembly 122 (in particular, the seal 124) and the vessel 131 (in particular, the upper surface of the second weir 136). Accordingly, the second weir 136 can include castellations or other arrangements of projections and gaps that promote this fluid flow.

FIG. 3A is a top isometric view of the agitator housing 141 and the agitator 140 shown in FIGS. 2A and 2B. The agitator elements 142 are elongated along axis E and arranged generally parallel to each other. In a particular embodiment shown in FIG. 3A, the agitator elements 142 are separated by fluid-transmissible openings, and in other embodiments, the agitator includes a base (e.g., a solid base), with the agitator elements 142 projecting upwardly from the base to form a plurality of movable compartments that are open to the workpiece above. Further details of such an arrangement are disclosed in pending U.S. application Ser. No. 11/603,940, filed Nov. 22, 2006 and incorporated herein by reference.

The agitator 140 reciprocates in a direction generally transverse to the elongation axis E, as is indicated by arrow R. The agitator 140 is supported toward one end by a first support 143, and toward the opposite end by a second support 144. The first support 143 is connected to a drive motor, and the second support 144 is connected to a linear guide structure, both of which are described in greater detail below with reference to FIGS. 4-5C. The first and second supports 143, 144 are enclosed at least in part in corresponding splash chambers 145, which are positioned to contain and dampen fluid splashing and/or sloshing that may result as a consequence of the reciprocating action of the agitator 140. Chamber covers 146 are carried by each of the supports 143, 144 and move with the supports 143, 144 relative to the corresponding splash chamber 145. Accordingly, the chamber covers 146 accommodate the motion of the agitator 140, and prevent or at least restrict fluid from splashing out of the splash chambers 145.

FIG. 3B is a bottom isometric view of the agitator housing 141 and the agitator 140 shown in FIG. 3A. In the illustrated arrangement, the agitator elements 142 are integrally formed with each other from a single piece of machined or cast stock that includes an encircling rim 147. An advantage of this arrangement is that it improves the rigidity of the agitator elements 142 and the agitator 140 overall, resulting in more consistent spacing between the agitator elements 142 and the workpiece adjacent to which they reciprocate. Couplings 148 at each end of the agitator 140 connect the agitator 140 to the first support 143 and the second support 144. The agitator housing 141 includes slots 149 that receive the agitator 140 and the couplings 148 and accommodate the reciprocal motion of the agitator 140 while also containing, at least in part, the fluid within the agitator housing 141. Accordingly, the slots 149 can be small enough to reduce significant splashing, which is further reduced by the presence of the splash chambers 145.

FIG. 3C is a cross-sectional illustration of the agitator 140 and agitator housing 141, taken substantially along line 3C-3C of FIG. 3A. FIG. 3C illustrates the agitator 140 positioned within the agitator housing 141, along with the first support 143 connected toward one end of the agitator 140 with one coupling 148, and the second support 144 connected toward the opposing end of the agitator 140 with another coupling 148. The couplings 148 and/or the agitator 140 extend through the slots 149, which accommodate reciprocal motion of the agitator 140 generally transverse to the plane of FIG. 3C. The splash chambers 145 extend around the first support 143 and the second support 144 to contain fluid that passes into the splash chamber 145 through the slots 149. The chamber covers 146 restrict or prevent fluid from splashing outside of the splash chambers 145.

FIG. 4 is a top isometric illustration of the agitator 140 and the agitator housing 141 installed in a process chamber 130. With the agitator housing 141 installed, the first support 143 and the second support 144 extend upwardly above the process location P and out of the corresponding splash chambers 145. For purposes of illustration, the chamber covers 146 (FIG. 3C) have been removed. The first support 143 is connected to a linear drive device 151, which is driven by a motor 150. Drive bellows 152 are positioned around the linear drive device 151 to protect it from the chemical environment within and adjacent to the process chamber 130, while allowing the motor 150 to drive the agitator 140 back and forth, as indicated by arrow R. The second support 144 extends out of the opposing splash chamber 145, where it is connected to a linear guide 153. The linear guide 153 supports the agitator 140 as the agitator 140 reciprocates, thereby maintaining the agitator elements 142 at a consistent spacing from the process location P. At the same time, the linear guide 153 is not so restrictive as to cause binding when the motor 150 drives the agitator 140 back and forth. Further details of particular arrangements for the linear guide 153 are described below with reference to FIGS. 5A-5C.

FIG. 5A is an exploded view of the linear guide 153 described above with reference to FIG. 4. The linear guide 153 includes an elongated, generally U-shaped guide rail 154 carried at opposing ends by corresponding mounts 157. A guide carriage 155 slides or rolls along the guide rail 154 and is attached to the second support 144 (FIG. 4) with a bracket 161. Guide bellows 156 are positioned on either side of the guide carriage 155 to protect the guide rail 154 and internal components from the local environment.

FIG. 5B is a cross-sectional illustration of the linear guide 153 described above with reference to FIG. 5A, after assembly. In the illustrated arrangement, the guide carriage 155 includes multiple rollers 158 that engage with and roll along the guide rail 154. In a particular arrangement, the rollers 158 include three rollers, illustrated as two first rollers 158 a and a second roller 158 b. In a particular aspect of this arrangement, the first rollers 158 a have a fixed relationship relative to the guide rail 154 in a direction transverse to the plane of FIG. 5B, while the second roller 158 b can be adjusted in the transverse direction to have a desired location relative to the guide rail 154 that reduces the tendency for the guide carriage 155 to bind with the guide rail 154. Further details of this arrangement are described below with reference to FIG. 5C.

FIG. 5C is a cross-sectional illustration of the linear guide 153, taken substantially along line 5C-5C of FIG. 5B. Although the section is taken through the second roller 158 b, the following discussion describes aspects of both the first rollers 158 a and the second roller 158 b. Linear guide mechanisms having the following characteristics are available from the Rollon Corporation of Sparta, N.J.

When seen from its end, (as in FIG. 5C) the guide rail 154 includes an inner side wall 159 a, an opposing outer side wall 159 b, an inner lip 160 a positioned above the inner side wall 159 a, and an outer lip 160 b positioned above the outer side wall 159 b. The illustrated roller 158 can make contact with any of these surfaces as it rolls along the guide rail 154 in a direction into and out of the plane of FIG. 5C.

When the roller 158 shown in FIG. 5C is one of the first rollers 158 a shown in FIG. 5B, its lateral position relative to the guide rail 154 is fixed. When the roller 158 corresponds to the second roller 158 b, its lateral position can be adjusted using an eccentric adjustment mechanism to move it laterally, as indicated by arrow L, relative to the guide rail 154. Accordingly, if the first rollers 158 a are in contact with the inner side wall 159 a, the second roller 158 b can be adjusted so as to be spaced apart from both the inner side wall 159 a and the outer side wall 159 b. Otherwise, if the first rollers 158 a are in contact with the inner side wall 159 a, and the second roller 158 b is in contact with the outer side wall 159 b, the carriage 155 may bind in the guide rail 154. By adjusting the second roller 158 b to allow at least some relative motion in the lateral direction L, the likelihood that the carriage 155 will bind is eliminated or at least reduced. At the same time, the arrangement of the rollers 158 and the guide rail 154 is such that a small amount of motion in the lateral direction L does not create a significant amount of motion in the vertical direction V. In this way, the vertical orientation of the agitator (which is carried by the guide carriage 155) remains fixed or at least approximately fixed so that the agitator does not shift upwardly and downwardly relative to the workpiece adjacent to which it reciprocates.

One manner in which the vertical motion of the carriage 155 is restricted is by virtue of the inner lip 160 a and the outer lip 160 b. The two lips 160 a-160 b are sloped so that if the roller 158 shifts (e.g., from right to left in FIG. 5C), the outer lip 160 b tends to drive the roller 158 back downwardly by virtue of its sloped orientation. If the roller 158 then moves back to the right, the inner lip 160 a performs the same operation. This arrangement reduces the amount of motion in the vertical direction V while allowing at least some motion in the lateral direction L, thus reducing the tendency for the guide carriage 155 to bind.

One feature of the foregoing arrangements described above with reference to FIGS. 1-5C is that the linear guide 153 is positioned to restrict the movement of the agitator 140 toward and away from the process location along a first axis (e.g., as indicated by arrow V in FIG. 5C). At the same time, the linear guide 153 allows linear translation of the agitator 140 along the reciprocation axis R, which is generally perpendicular to the vertical axis V. The linear guide 153 also allows for at least some movement of the agitator 140 along a third orthogonal axis perpendicular to the vertical axis V and the reciprocation axis R, as indicated by arrow L in FIG. 5C, to at least reduce the tendency for the agitator 140 to bind with the linear guide 155. This arrangement produces a more reliable reciprocation operation, while preventing or at least restricting variations in the distance between the agitator 140 and the workpiece W across the surface of the workpiece W. This in turn is expected to produce more consistent agitation over the surface of the workpiece W, which is expected to produce more consistent process results (e.g., more consistent deposition results) across the surface of the workpiece W.

Another feature of at least some of the foregoing embodiments is that the agitator 140 is actively driven at one end by the motor 150 and linear drive device 151, and supported (but not driven) at its opposite end by the linear guide 153. Put another way, the driving force that reciprocates the agitator 140 is directed through only one end of the agitator and only one end of the agitator elements 142. However, the agitator 140 is not cantilevered. Because the agitator 140 is not cantilevered, the agitator elements 142 are expected to have a more uniform separation from the workpiece W all across the workpiece W, thereby increasing the uniformity of the agitation produced at the process location P. In addition, as discussed above, the linear guide 153 is constructed to inhibit motion of the agitator 140 toward and away from the process location P, while allowing at least enough motion along the transverse axis L to prevent the agitator 140 from binding.

Still another feature of at least some of the foregoing embodiments is that the agitator 140 is integrated into a process chamber 130 that includes a thief or other electrode 133 d that may perform a thieving function. The electrode 133 d is positioned close to and above the edge of the workpiece W when the workpiece W is at the process location P. The location of the electrode 133 d above the process location P and outside the weir 135 is expected to reduce the likelihood for particulates to enter and contaminate the agitator chamber 129. Furthermore, the radial direction of the flow through and out of the process chamber 129 is further expected to carry particulates away from the agitator chamber 129 rather than into the agitator chamber 129. Accordingly, while the local flow adjacent to the workpiece W changes direction as a result of the agitator 140 reciprocating within the agitator chamber 129, the bulk flow is radially outwardly over the weir 135.

From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the invention. For example, the linear guide may have arrangements other than the particular roller arrangement described above, while still inhibiting motion of the agitator toward and away from the process location and at the same time allowing reciprocal motion of the agitator and preventing the agitator from binding. Certain aspects of the invention described in the context of particular embodiments may be combined or eliminated in other embodiments. For example, the agitator may be installed in process chambers having configurations other than that shown in FIG. 2. Further, while advantages associated with certain embodiments of the invention have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the invention. Accordingly, the invention is not limited except as by the appended claims. 

1. A system for processing microfeature workpieces, comprising: a vessel configured to receive a processing fluid at a process location; a fluid inlet positioned to direct the processing fluid into the vessel; a weir positioned above the process location and outwardly from the fluid inlet to receive the processing fluid moving radially outwardly from the fluid inlet; a workpiece support positioned to carry a microfeature workpiece at the process location; an agitator having an elongated agitator element proximate to the process location; a first support carrying the agitator proximate to a first end of the agitator element, and a second support carrying the agitator proximate to a second end of the agitator element opposite the first end; a motor operatively coupled to the first support and not the second support to drive the agitator along a linear path relative to the process location; and a linear guide engaged with the second support.
 2. The system of claim 1 wherein the agitator element is one of a plurality of elongated, spaced-apart agitator elements, with fluid-transmissible openings between neighboring agitator elements.
 3. The system of claim 1 wherein the linear guide is positioned to (a) restrict movement of the agitator toward and away from the process location along a first axis, (b) allow linear translation of the agitator along the linear path aligned with a second axis generally perpendicular to the first axis, and (c) allow for movement of the agitator along a third axis generally perpendicular to the first and second axes to at least reduce the tendency for the agitator to bind with the linear guide.
 4. The system of claim 3 wherein the linear guide includes a generally U-shaped channel having an upwardly facing opening, and wherein the channel carries rollers connected to the second support.
 5. The system of claim 4 wherein at least one of the rollers is in contact with a first sidewall of the channel, and wherein none of the remaining rollers contacts a second sidewall facing toward the first sidewall.
 6. The method of claim 5 wherein the channel includes lips extending inwardly toward each other from the upper ends of each of the sidewalls to restrict motion of the agitator toward and away from the process location.
 7. The system of claim 4 wherein at least one of the rollers has a fixed position relative to the agitator and wherein another of the rollers has an adjustable position relative to the agitator.
 8. The system of claim 1, further comprising first and second magnets positioned on opposite sides of the vessel to orient material applied to a microfeature workpiece at the process location.
 9. The system of claim 1 wherein the first and second supports extend upwardly away from the process location, and wherein the vessel includes first and second splash chambers, each extending upwardly from the process location and positioned around one of the first and second supports to contain fluid splashing.
 10. The system of claim 1, further comprising an electrode support positioned below the process location to carry multiple, independently controllable electrodes in fluid communication with the process location.
 11. The system of claim 1 wherein the agitator element has a generally pointed upper extremity and a generally pointed lower extremity.
 12. The system of claim 1, further comprising an electrode positioned apart from the workpiece support and above the process location.
 13. The system of claim 12 wherein the electrode is one of a plurality of electrodes, the one electrode being coupled to a potential at a first polarity, and wherein a subset of the electrodes are positioned in fluid communication with the process location and are coupled to a potential at a second polarity opposite the first, and wherein the workpiece support carries a contact coupled to a potential at the first polarity and positioned to contact a microfeature workpiece at the process location.
 14. The system of claim 1 wherein the weir is a first weir, and wherein the system further comprises a second weir positioned radially outwardly from the first weir, the electrode being positioned between the first weir and the second weir.
 15. A method for processing microfeature workpieces, comprising: directing processing fluid upwardly into a vessel toward a microfeature workpiece positioned at a process location of the vessel; directing the processing fluid radially outwardly adjacent to the microfeature workpiece and over a weir; and agitating the processing fluid adjacent to the microfeature workpiece with an agitator having an agitator element by: driving a first support positioned toward a first end of the agitator element; and guiding a second support along a linear guide path, without driving the second support, the second support being positioned toward a second end of the agitator element opposite the first end.
 16. The method of claim 15 wherein guiding the second support includes: at least restricting movement of the agitator toward and away from the process location along a first axis; allowing linear translation of the agitator along the linear path in a direction aligned with a second axis generally perpendicular to the first axis; and allowing for movement of the agitator along a third axis generally perpendicular to the first and second axes to at least reduce the tendency for the second support to bind.
 17. The method of claim 16 wherein allowing linear translation of the agitator along the linear path includes allowing a roller carried by the agitator to roll within a guide channel aligned along the linear path.
 18. The method of claim 17 wherein the roller is a first roller that rolls along a first sidewall of a U-shaped channel having an upwardly facing opening, and wherein allowing for movement of the agitator along the third axis includes allowing a second roller carried by the agitator to be out of contact with the first sidewall and a second sidewall of the channel facing toward the first sidewall of the channel.
 19. The method of claim 17 wherein the roller rolls along a first sidewall of a U-shaped channel having an upwardly facing opening and a lip extending at least partially across the opening, and wherein at least restricting movement of the agitator toward and away from the process location includes at least restricting motion of the roller via contact with the lip.
 20. The method of claim 15 wherein agitating the processing fluid includes agitating the processing fluid with a plurality of elongated, spaced-apart agitator elements having fluid-transmissible openings between neighboring agitator elements.
 21. The method of claim 15, further comprising containing processing fluid agitated by the agitator with a first splash chamber extending upwardly away from the process location around the first support, and with a second splash chamber extending upwardly from the process location around the second support.
 22. The method of claim 15, further comprising orienting material applied to the workpiece via a magnetic field in the vessel formed between first and second magnets positioned on opposite sides of the vessel.
 23. The method of claim 15, further comprising: depositing material on the workpiece from a plurality of anodes positioned in fluid communication with the workpiece; and attracting at least some of the material that would otherwise deposit on the workpiece to a cathode positioned apart from the workpiece and above the process location. 